An essential part of a backup and recovery strategy is managing backups after you create them. Backup management includes deleting obsolete backups and performing periodic checks to ensure that backups are available and usable.
A backup recorded in the Oracle Recovery Manager (RMAN) repository has one of the following status values:
Available, meaning that the backup is still present on disk or tape, as recorded in the repository
Expired, meaning that the backup no longer exists on disk or tape, but is still listed in the repository
Unavailable, meaning that the backup is temporarily not available for data recovery operations (because, for example, it is stored on a tape that is stored offsite or on a disk that is currently not mounted)
Backups can also be obsolete. An obsolete backup is, based on the currently configured retention policy, no longer needed to satisfy data recovery goals.
Maintenance tasks that you can perform in RMAN include the following:
Viewing details about your backups
Cross-checking your repository, which means checking whether backups listed in the repository exist and are accessible, and marking as expired any backups not accessible at the time of the cross-check
Deleting the record of expired backups from your RMAN repository
Deleting obsolete backups from the repository and from the backup media
Validating backups to ensure that a given backup is available and not corrupted
Note:
If a backup no longer exists, then immediately delete the backup record from the RMAN repository. Without an accurate record of available backups, you may discover that you no longer have complete backups of your database when you must perform a recovery.
Some tasks, such as periodic cross-checks of your backups, should be among the regularly scheduled components of your backup strategy.
If you use a fast recovery area for backup storage, then many maintenance activities are reduced or eliminated. The automatic storage space management mechanisms delete backups and other files as needed, thereby satisfying storage space demands for ongoing database operations without compromising the retention policy. However, you must monitor space usage in the fast recovery area to ensure that it is large enough to contain backups and other recovery-related files.